The present examples relate to an optical disk device and, more specifically, to an off-servo detection method for use during recording.
The background technologies in this field include those in JP-A-2001-344773, JP-A-8-30990, JP-A-2003-173551, and others. In these publications, an off-track-servo determination is made using the signal amplitude of a tracking error signal.
As another background technology, there is JP-A-2005-174389, for example. This publication describes a problem in that “a modulating signal of a sum-total signal cannot be detected, and this resultantly increases the difficulty in measuring the phase difference from a tracking error signal, thereby failing to determine a direction of the beam movement.” As means for solving the problem, there is a description that “provided are push-pull signal generation means for generating a push-pull signal, and on-track/off-track signal generation means for generating an on-track/off-track signal that determines the on-track/off-track state of a light spot based on a wobble frequency signal component that is superimposed on the push-pull signal to be derived when the light spot is moved by movement means.”
There is room for further improvement in techniques for detection of an off-track-servo condition during recording to a disk, by an optical disk device.